Abstract
We describe how string-based models such as HIJING and PYTHIA8/Angantyr models describe proton,
π
±
and
K
±
rapidity and transverse momentum (
p
T
) spectra from the
20
%
most central Be+Be collisions at the beam momentum range of 19 AGeV/c to 150 AGeV/c, recently measured in NA61/SHINE experiment at CERN. The HIJING model is extended with a more modern version of PYTHIA (version 6.4), which includes both the hard QCD and standard Lund string routines of PYTHIA8. As for Angantyr, the initial conditions for light nuclei (
A
≤
16
) are updated with a GLISSANDO (Glauber initial state simulation and more) harmonic oscillator shell (HOS) model density profile. It is found that different treatments of diffractive-like events implemented in both models do not lead to a satisfactorily description of the identified hadron spectra. We also compare the PYTHIA8/Angantyr/HOS results using two different mechanisms of the string break-up during the hadronization process, namely, the traditional one (Schwinger-model like) and the thermal one, where each hadron from string breaking is assigned an exponential hadron mass suppression weight times relevant spin and symmetry factors. Good agreement is generally obtained with the thermal model calculations at the whole SPS energies. In particular, it is found that the thermal model is more suited for the description of the identified hadron rapidity and
p
T
spectra, where there are more pions and kaons produced, and fewer protons at midrapidity
0
<
y
<
0.2
.